The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 4.2843\\[1 em]x_2 &= 0.3579+0.8975i\\[1 em]x_3 &= 0.3579-0.8975i \end{aligned} $$Polynomial $ x^3-5x^2+4x-4 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.